CN114377670B - Composite metal oxide catalyst for low-temperature SCR denitration and preparation method thereof - Google Patents
Composite metal oxide catalyst for low-temperature SCR denitration and preparation method thereof Download PDFInfo
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Abstract
The invention relates to a composite metal oxide catalyst for low-temperature SCR denitration and a preparation method thereof, and belongs to the technical field of catalysts. The catalyst is prepared by obtaining nano composite fibers from two catalyst precursor solutions through electrostatic spinning or centrifugal spinning and then performing dielectric barrier discharge calcination treatment, wherein one of the two catalysts is a vanadium-titanium SCR catalyst, and the main component is V 2 O 5 ‑WO 3 /TiO 2 Or V 2 O 5 ‑MoO 3 /TiO 2 Wherein the V content is 1-5wt.%, and the W or Mo content is 1-10wt.%; the other is an oxidation catalyst FMn with mullite structure x O y Wherein the mol ratio of F to Mn is 1:1-2,F and is selected from Sm, la, ce, pr, eu, gd or Y; the mass ratio of the oxidation catalyst to the vanadium-titanium SCR catalyst is 1: (1-10).
Description
Technical Field
The invention relates to a low-temperature catalyst, in particular to a composite metal oxide catalyst for low-temperature SCR denitration and a preparation method thereof, and belongs to the technical field of catalysts.
Background
Nitrogen oxides (NOx) are one of the major atmospheric pollutants, mainly comprising Nitric Oxide (NO) and nitrogen dioxide (NO 2 ). The NOx which can exist stably in the atmosphere can bring about environmental problems such as acid rain, photochemical smog, ozone layer damage and the like, and can also harm the health of human bodies. In recent years, as the total energy consumption of China is continuously increased, fossil energy such as coal is continuously consumed, NOx is always kept at a higher emission amount, and serious environmental pollution is caused.
In order to meet the specified emission requirements, a series of nitrogen oxide control technologies have been developed for coal-fired power plants and industrial boilers. The Selective Catalytic Reduction (SCR) technology has the advantages of high denitration efficiency (more than 90 percent), good product selectivity, simple system operation control, mature and reliable technology and the like, becomes a widely applied denitration technology in the coal-fired power plant at present, and has good application prospect in denitration in non-electric industries such as industrial boilers and the like.
Although the research and development of vanadium-titanium SCR catalyst V 2 O 5 -WO 3 /TiO 2 Or V 2 O 5 -MoO 3 /TiO 2 The method has been successfully applied at present, but still has the defect of higher working temperature, and has outstanding denitration performance only at 300-400 ℃. Therefore, development of SCR catalysts with high activity at low temperatures of 150-300 ℃ has been the goal of researchers worldwide.
Disclosure of Invention
The invention aims to provide a preparation method of a composite metal oxide catalyst for low-temperature SCR denitration, which aims to solve the problems of narrow temperature range and poor low-temperature performance of the existing SCR catalyst.
The invention mainly adopts the technical scheme that:
a composite metal oxide catalyst for low-temp SCR denitration is prepared from two catalyst precursors through electrostatic spinning or centrifugal spinning to obtain nano-composite fibres, and calcining by dielectric barrier discharge
A vanadium-titanium SCR catalyst contains V as main component 2 O 5 -WO 3 /TiO 2 Or V 2 O 5 -MoO 3 /TiO 2 Wherein the V content is 1-5wt.%, and the W or Mo content is 1-10wt.%;
the other is an oxidation catalyst FMn with mullite structure x O y Wherein the mol ratio of F to Mn is 1:1-2,F and is selected from Sm, la, ce, pr, eu, gd or Y;
the mass ratio of the oxidation catalyst to the vanadium-titanium SCR catalyst is 1: (1-10).
Aiming at the defects of the existing catalytic denitration technology, the inventor develops and researches a composite SCR catalyst based on a vanadium-titanium SCR catalyst on the basis of long-term research and development of the flue gas denitration catalyst so as to improve the low-temperature denitration efficiency of the vanadium-titanium SCR catalyst. Test results show that the composite SCR catalyst successfully widens the high-efficiency reaction temperature window of the vanadium-titanium SCR catalyst, improves the denitration efficiency of the vanadium-titanium SCR catalyst below 300 ℃, and the preparation method of the composite SCR catalyst is simple and easy to operate, and is a method with low cost and capability of preparing the high-performance SCR catalyst in a large amount.
The inventor researches and discovers that after the vanadium-titanium SCR catalyst is compounded with the oxidation catalyst, NO can form intermediate species such as nitrite on the oxidation catalyst, and the intermediate species can migrate to the surface of the vanadium-titanium SCR catalyst and react with ammonia species adsorbed on the surface of the vanadium-titanium SCR catalyst to generate nitrogen and water, so that the defect of poor low-temperature performance caused by weak catalytic oxidation of NO at low temperature of the vanadium-titanium SCR catalyst is overcome. The composite method of the two catalysts adopts electrostatic spinning combined with dielectric barrier discharge calcination, so that the mutual influence between atoms in the two catalyst components can be avoided, and the low-temperature denitration efficiency of the SCR catalyst is improved while the good high-temperature activity of the SCR catalyst is maintained.
Preferably, the mass ratio of the oxidation catalyst to the vanadium-titanium SCR catalyst is 1: (1-2). The purpose of adding the oxidation catalyst is to improve the low-temperature activity of the medium-high temperature SCR catalyst, but an excessive amount of the oxidation catalyst tends to cause a decrease in the high-temperature performance in the catalyst itself. The mass ratio of the oxidation catalyst to the vanadium-titanium SCR catalyst is optimally 1:1.
Preferably, the diameter of the nano composite fiber obtained by spinning is 100-900nm.
In the present invention, the oxidation catalyst is preferably SmMn x O y 。
The preparation method of the composite metal oxide catalyst for low-temperature SCR denitration comprises the following steps:
s1, respectively preparing precursor solutions of the vanadium-titanium SCR catalyst and the oxidation catalyst as spinning solutions, preparing composite metal oxide fibers through electrostatic spinning or centrifugal spinning,
s2, calcining the composite metal oxide fiber through dielectric barrier discharge to obtain the composite metal oxide catalyst.
Preferably, the oxidation catalyst SmMn x O y The preparation method of the precursor solution comprises the following steps:
1) Mixing polyethylene glycol, pluronic F127 and water, and heating to dissolve to obtain solution A containing surfactant; mixing a manganese-containing precursor, a samarium-containing precursor and the solution A until the manganese-containing precursor, the samarium-containing precursor and the solution A are dissolved to obtain a solution B;
2) Adding H to solution B 2 O 2 Solution of manganese element and H 2 O 2 The molar ratio is 1:1.2-1.5;
3) Stirring the mixed solution obtained in the last step for more than 2 hours, then adding polyvinylpyrrolidone (PVP) and continuously stirring for 10-24 hours to obtain the oxidation catalyst SmMn x O y Precursor solution. The manganese-containing precursor is typically manganese nitrate and the samarium-containing precursor is typically samarium nitrate.
In the invention, polyethylene glycol is used as a surfactant, generally PEG-400-600 is adopted, and the high molecular weight is easy to cause adhesion.
Preferably, the method of electrostatic spinning in S1 is as follows: respectively extracting two precursor solutions by using a 5-20 mL syringe, connecting a needle head with a 10-20 kV direct-current high-voltage negative power supply, carrying out electrostatic spinning to form composite fibers, and placing the composite fibers in a vacuum box at 20-50 ℃ for drying for 24 hours.
Preferably, the specific process of calcining the composite metal oxide fiber through dielectric barrier discharge in S2 is as follows: under the atmosphere of oxygen, nitrogen and argon or the mixture of more than two gases, the output voltage and the output frequency are respectively 8-12 kV and 8-10 kHz, so that the gas inside the reactor breaks down to generate dielectric barrier discharge, and the dielectric barrier discharge is kept for 30-60 min, thus preparing the composite metal oxide catalyst.
Preferably, the preparation method of the vanadium-titanium SCR catalyst precursor solution comprises the following steps: dissolving vanadium-containing precursor, tungsten-containing precursor/molybdenum-containing precursor and titanium-containing precursor in water, stirring thoroughly, adding polyvinylpyrrolidone (PVP), stirring for 10-24 hr to obtain V 2 O 5 -WO 3 /TiO 2 Or V 2 O 5 -MoO 3 /TiO 2 Is a precursor solution of (a). The vanadium-containing precursor is typically ammonium metavanadate, the tungsten-containing precursor is typically ammonium metatungstate, the molybdenum-containing precursor is typically ammonium molybdate tetrahydrate, and the titanium-containing precursor is one of tetrabutyl titanate or titanium sulfate. The vanadium-titanium based SCR catalyst of the present invention may be prepared using techniques known in the art.
The application of the composite metal oxide catalyst in the aspect of low-temperature SCR denitration is characterized in that the lower limit of the low-temperature denitration is 150 ℃. The composite metal oxide catalyst for low-temperature SCR denitration can widen the temperature lower limit of a high-efficiency temperature window (more than 300 ℃) of a vanadium-titanium SCR catalyst to 150 ℃, and the denitration efficiency is more than 90%.
Compared with the prior art, the invention has the advantages that:
1. compared with vanadium-titanium SCR catalyst, the invention uses the composite oxidation catalyst SmMn x O y The obtained composite metal oxide catalyst not only remarkably improves the low-temperature denitration efficiency, but also has no obvious influence on the middle-high-temperature denitration performance of the original vanadium-titanium SCR catalyst, and widens the temperature window of high-efficiency denitration;
2. compared with the traditional dipping method, coprecipitation methodThe method adopts electrostatic spinning and dielectric barrier discharge calcination to oxidize the catalyst SmMn x O y The preparation method can controllably reduce the distance between different active sites on two catalysts to a micron level, and realize the close contact between the sites, thus obtaining the wide-temperature composite metal oxide catalyst with good performance.
Drawings
FIG. 1 is a scanning electron microscope image of a composite metal oxide catalyst prepared in example 2 of the present invention.
Detailed Description
The technical scheme of the invention is further specifically described by the following specific examples. It should be understood that the practice of the invention is not limited to the following examples, but is intended to be within the scope of the invention in any form and/or modification thereof.
In the present invention, unless otherwise specified, all parts and percentages are by weight, and the equipment, materials, etc. used are commercially available or are conventional in the art. The methods in the following examples are conventional in the art unless otherwise specified. The reagents used in the examples described below, unless otherwise specified, were purchased from conventional biochemical reagent stores.
Pluronic F127 powder, purchased from Sigma-Aldrich.
Example 1
The core of the invention is a preparation method of a composite metal oxide catalyst for low-temperature SCR denitration, which comprises two main steps of electrostatic spinning and plasma calcination, and the method comprises the following steps:
s1, preparing composite metal oxide catalyst by electrostatic spinning method
1) Preparation of spinning precursor solution:
two precursor solutions, one of which is used for preparing oxidation catalyst SmMn x O y The preparation method of the precursor solution comprises the following steps:
preparing a solution containing a surfactant, dissolving PEG-600 and Pluronic F127 in deionized water, and heating in a water bath at 60 ℃ until the solution is completely dissolved to obtain a solution A;
dissolving precursor manganese nitrate and samarium nitrate in the solution A, and obtaining a solution B after complete dissolution;
then add 30% H 2 O 2 If the manganese nitrate is 1 mol part, the hydrogen peroxide is 1.3 mol parts;
after stirring the mixture at room temperature for at least 2 hours, polyvinylpyrrolidone (PVP) is added and stirring is continued for 10 to 24 hours for standby.
The preparation method of the precursor solution is as follows:
dissolving precursor ammonium metavanadate, ammonium metatungstate, tetrabutyl titanate or titanium sulfate in deionized water, magnetically stirring the solution for 0.5-2 hours, and then adding polyvinylpyrrolidone (PVP) and continuously stirring for 10-24 hours for later use.
2) And (3) electrostatic spinning: and respectively extracting the two precursor solutions prepared in the steps by using a 5-20 mL syringe, installing a 21G needle, fixing the needle on a syringe pump, connecting the needle with a direct-current high-voltage negative power supply, covering an aluminum foil by a receiving roller, grounding the receiving roller, and carrying out electrostatic spinning, wherein the direct-current negative power supply voltage is 10-20 kV. The two precursors form Taylor cones on a needle connected with a high-voltage power supply, the repulsive force of an electric field overcomes the surface tension of the precursors, so that the precursors stretch and whip in the electric field and volatilize part of solvents, and finally, composite fibers are formed on a receiving device;
3) The obtained composite fiber is dried in a vacuum box at 20-50 ℃ for 24 hours.
S2, calcining composite fiber through dielectric barrier discharge
The sample is placed between the rod-shaped electrode in the discharge reactor and the inner wall of the quartz tube, and the gas can be oxygen, nitrogen, argon or a mixture of more than two gases. One end of a high-voltage high-frequency alternating current power supply is connected with a rod-shaped electrode of the low-temperature plasma reactor, the other end of the high-voltage high-frequency alternating current power supply is connected with an aluminum foil wrapped on the outer wall of a quartz tube and is grounded, and output voltage and frequency are respectively adjusted to 8-12 kV and 8-10 kHz, so that gas inside the reactor breaks down to generate dielectric barrier discharge, and the dielectric barrier discharge is kept for 30-60 min, and the composite metal oxide catalyst is prepared.
Example 2
On the basis of example 1, this example further defines that the oxidation catalyst is determined to have a mullite structure SmMn with excellent NO oxidation performance 2 O 5 Wherein the molar ratio of Sm to Mn is 1:2; SCR catalyst is defined as V 2 O 5 -WO 3 /TiO 2 Wherein V is 2 O 5 The content is 1 percent: WO (WO) 3 The content is 5%, and the carrier is TiO 2 94% (tetrabutyl titanate for precursor); the mass ratio of the two catalysts is 1:1.
The preparation method of the composite metal oxide catalyst for low-temperature SCR denitration comprises the following specific steps:
s1, preparing composite metal oxide catalyst by electrostatic spinning method
S1.1 oxidation catalyst SmMn 2 O 5 Preparing a precursor:
preparing a surfactant-containing solution: PEG-600 and Pluronic F127 are dissolved in deionized water, and heated in a water bath at 60 ℃ until the dissolution is complete, so as to obtain solution A;
dissolving manganese nitrate and samarium nitrate in a molar ratio of 2:1 in the solution A, and obtaining a solution B;
then add 30% H 2 O 2 Solution of manganese nitrate and H 2 O 2 The mol ratio of the solution is 1:1.3;
the mixture was stirred at room temperature for 2 hours, polyvinylpyrrolidone (PVP) was added and stirring was continued for 10 hours to obtain solution C for use.
S1.2, preparation of vanadium-titanium SCR catalyst precursor: dissolving precursors of ammonium metavanadate, ammonium metatungstate and tetrabutyl titanate in deionized water, magnetically stirring the solution for 2 hours, adding polyvinylpyrrolidone (PVP) and continuously stirring for 10 hours to obtain a solution D for later use.
S1.3, preparing composite metal oxide fibers by an electrostatic spinning method:
extracting the precursor solutions C and D prepared in the steps by using a 10mL syringe respectively, installing a 21G needle head, connecting 15kV direct current negative power supply voltage for electrostatic spinning, and obtaining composite fibers on a receiving roller device;
the composite fiber obtained in the above step was dried in a vacuum oven at 20 ℃ for 24 hours to obtain an uncalcined composite fiber.
S2, calcining composite fiber through dielectric barrier discharge
And (3) putting the composite fiber obtained in the steps into a plasma reactor, exposing the composite fiber to a mixed atmosphere of 5% oxygen and 95% nitrogen, maintaining the mixed atmosphere for 30min, adjusting the output voltage and the frequency to 10kV and 8kHz respectively, treating the composite fiber in a dielectric barrier discharge mode for 30min, and finally obtaining the composite metal oxide catalyst for low-temperature SCR denitration.
FIG. 1 is a scanning electron microscope image of a composite metal oxide catalyst prepared in example 2 of the present invention, in which the left and right images show the variation of average diameter of composite fibers between 600nm and 500 m.
Application example catalyst Activity test
Catalyst activity tests were conducted on 0.1g of the composite metal oxide catalyst prepared in Experimental example 2 and a common vanadium-titanium SCR catalyst, and catalyst activity evaluation was conducted in a fixed bed reactor having an inner diameter of 5 mm.
Preparation of common vanadium-titanium SCR catalyst (isovolumetric impregnation method):
1) Weighing proper amount of ammonium metavanadate powder, dissolving in deionized water, and adding oxalic acid (H) 2 C 2 O 4 ·2H 2 O) the dissolution aid, the molar quantity is twice that of ammonium metavanadate. The mixed solution was stirred continuously at 60℃until the solution turned deep blue (VO 2 + )；
2) Weighing a proper amount of ammonium metatungstate powder, and dissolving the ammonium metatungstate powder in deionized water. Adding oxalic acid (H) 2 C 2 O 4 ·2H 2 O) solubilizing aid, the molar quantity is twice that of ammonium metatungstate. Continuously stirring the mixed solution at 60 ℃ until the ammonium metatungstate is completely dissolved;
3) Weighing a proper amount of TiO 2 The powder was measured and the appropriate ammonium metavanadate solution and ammonium metatungstate solution (solution volume and carrierEqual volume), tiO 2 Pouring the powder into a mixed solution of an ammonium metavanadate solution and ammonium metatungstate, fully stirring, and standing overnight;
4) The catalyst was dried at a constant temperature of 110℃for 300min overnight. Calcining in the atmosphere condition in a muffle furnace at 500 ℃ for 300min at a heating rate of 10 ℃/min in the heating process to obtain the preparation V by the impregnation method after calcining 2 O 5 -WO 3 /TiO 2 A catalyst.
O 2 、NO/N 2 、NH 3 /N 2 Mixing with N2 under control of mass flowmeter to obtain simulated smoke with a composition of 5% O 2 、350ppmNO、350ppmNH 3 N2 is balance gas, airspeed is 73000h -1 . The reaction temperature is 150-300 ℃, NH 3 and/NO is 1. The gas components were detected by an infrared flue gas analyzer to compare the denitration efficiency of the composite metal oxide catalyst of the present invention with that of a conventional vanadium-titanium SCR catalyst at different temperatures, and the detection results are shown in table 1.
Table 1 denitration efficiency comparison results (%)
| Temperature (. Degree. C.) | 150 | 175 | 200 | 225 | 250 | 300 |
| Vanadium-titanium SCR catalyst | 9.99 | 14.19 | 20.57 | 29.03 | 42.78 | 95.83 |
| The composite catalyst of the invention | 91.41 | 100 | 100 | 100 | 100 | 100 |
The invention focuses on the synergistic strengthening effect of the two catalysts on the low-temperature denitration performance after compounding. Experiments prove that the oxidation catalyst SmMn 2 O 5 After the catalyst is compounded with the existing vanadium-titanium SCR catalyst, the catalytic performance of the vanadium-titanium SCR catalyst is enhanced. The composite metal oxide catalyst has catalytic application in flue gas denitration, wherein the low temperature is 150-300 ℃, and the denitration efficiency can reach more than 90% at 150 ℃.
In addition, the inventors have compared the oxidation catalyst SmMn 2 O 5 The mass ratio of the catalyst to the vanadium-titanium SCR catalyst is 1:1 and the catalyst activity is 1:2 respectively (measured under the same experimental conditions). When the oxidation catalyst is SmMn 2 O 5 When the mass ratio of the catalyst to the vanadium-titanium SCR catalyst is 1:2, the denitration efficiency of the obtained composite metal oxide catalyst at 150 ℃ is 50.79%, and the denitration efficiency of the composite metal oxide catalyst at 175 ℃ is 88.01%; when the oxidation catalyst is SmMn 2 O 5 When the mass ratio of the catalyst to the vanadium-titanium SCR catalyst is 1:1, the obtained composite metal oxide catalyst is at the temperature of 150 DEG CThe denitration efficiency is 91.41 percent and the denitration temperature is 100 percent, and the amount of the oxidation catalyst in the composite catalyst is proved to determine the low-temperature denitration performance of the composite catalyst, namely, the higher the content of the oxidation catalyst is, the better the low-temperature denitration performance of the composite catalyst is.
In conclusion, the composite metal oxide catalyst for low-temperature SCR denitration improves the denitration efficiency of the vanadium-titanium SCR catalyst at low temperature (150-300 ℃) by 4.17-85.81% under the same conditions, and obviously improves the low-temperature performance.
Example 3
Based on the preparation method of the composite metal oxide catalyst for low-temperature SCR denitration, the formula of the oxidation catalyst is changed, and the performance of the composite catalyst in a low-temperature range is observed under the same reaction conditions. Test method the activity test of the catalyst is referred to, and the comparison result of the activity of the composite metal oxide catalysts of different oxidation catalysts and the activity of the common vanadium-titanium SCR catalyst is shown in Table 2.
TABLE 2 comparative catalyst Activity (%)
As can be seen from table 2, when the oxidation catalyst in the composite metal oxide catalyst is changed to other formulation having oxidation ability, the improvement of denitration efficiency at low temperature still exists, and the improvement effect is changed with the change of oxidation ability, the stronger the oxidation ability, the better the improvement effect. Therefore, the preparation method of the composite metal oxide catalyst for low-temperature SCR denitration provided by the invention has certain universality for different composite metal oxides.
In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, so that the same or similar parts between the embodiments are referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The composite metal oxide catalyst for low-temperature SCR denitration and the preparation method thereof provided by the invention are described in detail. The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to facilitate an understanding of the method of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.
Claims (5)
1. A composite metal oxide catalyst for low temperature SCR denitration, characterized by: the catalyst is prepared by obtaining nano composite fibers from two catalyst precursor solutions through electrostatic spinning or centrifugal spinning and then performing dielectric barrier discharge treatment, wherein the two catalysts are prepared by adopting a preparation method of the nano composite fibers
A vanadium-titanium SCR catalyst contains V as main component 2 O 5 -WO 3 /TiO 2 Or V 2 O 5 -MoO 3 /TiO 2 Wherein the V content is 1-5 wt%, and the W or Mo content is 1-10 wt%;
the other is an oxidation catalyst SmMn with mullite structure x O y Wherein the molar ratio of F to Mn is 1: 1-2;
the oxidation catalyst SmMn x O y The mass ratio of the catalyst to the vanadium-titanium SCR catalyst is 1: (1-2);
the oxidation catalyst SmMn x O y The preparation method of the precursor solution comprises the following steps:
1) Mixing polyethylene glycol, pluronic F127 and water, and heating to dissolve to obtain solution A containing surfactant; mixing a manganese-containing precursor, a samarium-containing precursor and the solution A until the manganese-containing precursor, the samarium-containing precursor and the solution A are dissolved to obtain a solution B;
2) Adding H to solution B 2 O 2 Solution of manganese element and H 2 O 2 The molar ratio is 1: 1.2-1.5;
3) Stirring lastThe mixed solution obtained in the step is added with polyvinylpyrrolidone (PVP) for stirring for 10-24 hours to obtain an oxidation catalyst SmMn x O y A precursor solution;
the preparation method of the vanadium-titanium SCR catalyst precursor solution comprises the following steps: dissolving a vanadium-containing precursor, a tungsten-containing precursor/a molybdenum-containing precursor and a titanium-containing precursor in water, fully stirring, adding polyvinylpyrrolidone (PVP), and continuously stirring for 10-24 hours to obtain V 2 O 5 -WO 3 /TiO 2 Or V 2 O 5 -MoO 3 /TiO 2 Is a precursor solution of (a);
the diameter of the nano composite fiber obtained by spinning is 100-900nm.
2. A method for preparing the composite metal oxide catalyst for low-temperature SCR denitration according to claim 1, which is characterized by comprising the steps of:
s1, respectively preparing the vanadium-titanium SCR catalyst precursor solution and an oxidation catalyst SmMn x O y The precursor solution is used as spinning solution to prepare the composite metal oxide fiber through electrostatic spinning or centrifugal spinning,
s2, treating the composite metal oxide fiber through dielectric barrier discharge to obtain the composite metal oxide catalyst.
3. The preparation method according to claim 2, characterized in that: the electrostatic spinning method in S1 comprises the following steps: respectively extracting the two precursor solutions by using a 5-20 mL syringe, connecting a needle head with a 10-20 kV direct-current high-voltage negative power supply, carrying out electrostatic spinning to form composite fibers, and placing the composite fibers in a vacuum box at 20-50 ℃ for drying for 24 hours.
4. The preparation method according to claim 2, characterized in that: the specific process of treating the composite metal oxide fiber through dielectric barrier discharge in the S2 is as follows: under the atmosphere of oxygen, nitrogen and argon or the mixture of more than two gases, the output voltage and the output frequency are respectively 8-12 kV and 8-10 kHz, so that the gas inside the reactor breaks down to generate dielectric barrier discharge, and the dielectric barrier discharge is kept for 30-60 min, thus preparing the composite metal oxide catalyst.
5. The use of a composite metal oxide catalyst for low temperature SCR denitration according to claim 1, wherein the low temperature denitration temperature is 150 ℃.
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